From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E25EC021B3 for ; Thu, 20 Feb 2025 15:48:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 18D80280191; Thu, 20 Feb 2025 10:48:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 13F3428018F; Thu, 20 Feb 2025 10:48:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EAB432802F5; Thu, 20 Feb 2025 10:48:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id D10B52802F2 for ; Thu, 20 Feb 2025 10:48:51 -0500 (EST) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 891F316247F for ; 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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1740066529; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Le1TAkt+6NjmQn+udaiioQ5/WEdQIHbgKao1ry4A1a4=; b=uEbEfwMBdiLweHl1BewdWQXmm21EG06W33jVVVmpsEXZ21dlUfRzNeHmF9QPNcnTQRcGiF T33qW43YE/Gbn6KthuXtAVdf8zKlcBI5FPvtm6DqCbktY1+d0T+ycMxsWwEfZMhfWM73/6 Yqk62IwR49SjPszry/9Qi5o1JoDu04A= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E820C16F3; Thu, 20 Feb 2025 07:49:06 -0800 (PST) Received: from [10.163.39.71] (unknown [10.163.39.71]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 278DF3F59E; Thu, 20 Feb 2025 07:48:45 -0800 (PST) Message-ID: Date: Thu, 20 Feb 2025 21:18:42 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6/6] selftests/mm: Don't fail uffd-stress if too many CPUs To: Brendan Jackman , Lorenzo Stoakes , Andrew Morton , Shuah Khan Cc: Mateusz Guzik , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250220-mm-selftests-v1-0-9bbf57d64463@google.com> <20250220-mm-selftests-v1-6-9bbf57d64463@google.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20250220-mm-selftests-v1-6-9bbf57d64463@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C7BF91C0024 X-Stat-Signature: gp438jaezpjnhb7yebpcxditg4jk1mbf X-Rspam-User: X-HE-Tag: 1740066529-692324 X-HE-Meta: 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 RVyhWNO8 PbaZzCDViDBw0WZKP/19kl290FeweuT7R7G0Q1HDcIXa98iAb1si/r+r8Wt6XNzpMMJvMl8hZcEapvogrKIpyfOtMqKX2LK/0i06SKdg7SW245nS7f0XQ4fkHM0fKICLDcDTQtOX+Y7jRbEyPEQyeWu7JYO/iIah7f50HH2gI01o4T/4arRZ2qTl5THnr64WMdhxR X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 20/02/25 8:33 pm, Brendan Jackman wrote: > This calculation divides a fixed parameter by an environment-dependent > parameter i.e. the number of CPUs. > > The simple way to avoid machine-specific failures here is to just put a > cap on the max value of the latter. I haven't read the test, but if nr_cpus is being computed, then this value must be important to the test somehow? Would it potentially be wrong to let the test run for nr_cpus != actual number of cpus? Also, if the patch is correct then will it be better to also print a diagnostic telling the user that the number of cpus is going to be capped for the test to run? > > Suggested-by: Mateusz Guzik > Signed-off-by: Brendan Jackman > --- > tools/testing/selftests/mm/uffd-stress.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c > index 1facfb79e09aa4113e344d7d90dec06a37264058..f306accbef255c79bc3eeba8b9e42161a88fc10e 100644 > --- a/tools/testing/selftests/mm/uffd-stress.c > +++ b/tools/testing/selftests/mm/uffd-stress.c > @@ -453,6 +453,10 @@ int main(int argc, char **argv) > } > > nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); > + if (nr_cpus > 32) { > + /* Don't let calculation below go to zero. */ > + nr_cpus = 32; > + } > > nr_pages_per_cpu = bytes / page_size / nr_cpus; > if (!nr_pages_per_cpu) { >